Morphological and physiological behaviour of sweet cherry 'somaclone' HS plants in field

We reported earlier that somaclonal variant HS (HS), regenerated from Prunus avium `Hedelfinger' (H) leaf explants, showed reduced apical dominance both in vitro and in vivo. In this report we found that the somaclone HS, showed reduced vegetative vigour as determined by trunk circumference and tree height nevertheless natural architecture of the tree was preserved. HS canopy was less crowded as to compare to H and leaves were shorter with a shorter petiole, they were better spaced out as indicated by internodes length. HS had a significantly thinner cuticle and wax layer compared to H leaves surface. Histological analysis of leaves also showed that HS had thicker mesophyll and palisade the latter composed of more than one layer which, together with increased stomatal density, are distinguishing signs of extensive exposure of leaves to sun. Chlorophyll a and chlorophyll b content did not differ between H and HS, β-carotene content was slightly lower in HS leaves. However no significant differences were found between the two genotypes in terms of net photosynthesis, intercellular CO₂ concentration, leaf transpiration and water use efficiency. HS flowered 1-year later than H and number of flowers was reduced. Fruit size, shape, skin colour change during the ripening process and the main parameters of fruit quality as assessed in the wild type and the somaclone were basically the same.